JP2001100194A - Reflective liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective liquid crystal display element which achromati cally displays a bright white color with high contrast with a structure using only one polarizing film. SOLUTION: A twist angle of a nematic liquid crytal is set as 0-90 deg.. Relations among birefringence of the liquid crystal ΔnLC, thickness of the liquid crystal layer dLC and retardation of a polymer film RFILM are set as ΔnLC.dLC=0.20 to 0.30 μm and RFILM-ΔnLC.dLC=-0.20 to -0.05 μm. Defining the twist direction of the nematic liquid crystal toward the lower substrate side seen from the upper substrate side as positive, the angle between a reference line and the direction of long molecular axis of the liquid crystal closest to the one substrate as ϕLC, the angle between the reference line and the direction of the slow axis of the polymer film as ϕF and the angle between the reference line and the direction of the absorption or transmission axis of the polarizing film as ϕP, ϕF-ϕLC is set as -40 to -25 deg. and ϕP-ϕF is set as +50 to +80 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display elements are thin and light, and thus are widely used in various applications including displays for portable information terminals. The liquid crystal display element is a light-receiving element that performs display by changing the light transmission intensity without emitting light by itself, and can be driven with an effective voltage of several volts, so it has a reflector under the liquid crystal display element If it is used as a reflection type in which a display is viewed by reflected light of external light, a display element with extremely low power consumption is obtained.

A conventional reflection type color liquid crystal display device comprises a liquid crystal cell provided with a color filter and a pair of polarizing films disposed so as to sandwich the liquid crystal cell. The color filter is provided on one substrate of the liquid crystal cell, and the color filter is formed on the substrate, and the transparent electrode is further formed thereon. By applying a voltage to the liquid crystal cell, the orientation of the liquid crystal molecules is changed to change the light transmittance of each color filter, thereby performing color display.

The transmittance of one polarizing plate is at most 45%.
At this time, the transmittance of the polarized light parallel to the absorption axis of the polarizing film is almost 0%, and the transmittance of the perpendicular polarized light is about 9%.
0%. Therefore, in a reflection type liquid crystal display element using two polarizing plates, light is emitted four times through the polarizing film.

(0.9) ⁴ × 50% = 32.8%

[0006] The reflectance is at most about 3 even for a black and white panel.
3%.

Therefore, in order to make the display brighter, there have been proposed some configurations in which only one polarizing film is provided on the upper side of the liquid crystal cell and the liquid crystal cell is sandwiched between one polarizing film and a reflection plate (for example, see, for example, Japanese Patent Application Laid-Open No. HEI 9-157556). JP-A-7-146469,
JP-A-7-84252). In this case, since the light passes through the polarizing film only twice, when the absorption of the color filter is not considered

(0.9) ² × 50% = 40.5%

Thus, an improvement in reflectance of up to about 23.5% can be expected with respect to the configuration using two polarizing films.

A reflective color liquid crystal display device (Japanese Patent Application Laid-Open No. 6-308481) which performs birefringence of a twisted nematic liquid crystal layer of a liquid crystal cell without using a color filter and performs colored display with a polarizing film, and a liquid crystal layer And a color liquid crystal display device utilizing the birefringence of a retardation film (JP-A-6-175125, JP-A-6-3010)
No. 06 publication) has been proposed.

[0011]

However, a reflective liquid crystal display device using two polarizing films has a reflectance sufficient to obtain sufficient brightness when color display is performed by using a color filter for this device. There was a problem that it could not be secured.

In a reflection type liquid crystal display device having a single polarizing film, when a color display is performed by using a color filter for this device to increase the reflectance and secure the brightness, the conventional structure is not used. However, black-and-white achromatic display is difficult, and in particular, there is a problem that reflectance is low and achromatic black display is difficult.

Further, a reflection type liquid crystal display element for performing a colored display with a polarizing film and a birefringence of a twisted nematic liquid crystal layer of a liquid crystal cell without using a color filter, and a birefringence between a liquid crystal layer and a retardation film are used. Since the color liquid crystal display element has no color filter, even if two polarizing films are used, it is possible to secure a reflectance sufficient to obtain practical brightness. However, since color display is performed using birefringent coloring, 16 gradations 409
In principle, multi-gradation / multi-color display such as 6-color display or 64-gradation full-color display is difficult, and the color purity and the color reproduction range are narrow.

Further, the reflection type liquid crystal display device in the black and white display mode also has a problem that a high white reflectance cannot be obtained when two polarizing films are used.

In view of such circumstances, it is an object of the present invention to provide a reflective liquid crystal display device which can provide a bright white display, a high contrast, and an achromatic monochrome display.

[0016]

In order to achieve the above object, the present invention has the following arrangement.

That is, the reflection type liquid crystal display element of the present invention is
A liquid crystal cell in which nematic liquid crystal is sealed between a pair of substrates,
Polarizing film disposed on one substrate side of the liquid crystal cell
And disposed between the polarizing film and the liquid crystal cell.
Polymer film and light reflection arranged on the other substrate side
And a nematic between the pair of substrates.
Liquid crystal twist angle is 0 ° ~ 90 °, the nematic
Birefringence Δn of liquid crystal_LCAnd liquid crystal layer thickness d_LCAnd the product Δn_LC・ D_LC
Is 0.20 to 0.30 μm, and the product Δn_LC・ D _LCAnd said
Retardation R of polymer film_FilmAnd R
_Film−Δn_LC・ D _LCThe birefringence difference ΔR defined as −0.
20 μm to −0.05 μm, which is different from the one substrate side
Viewed from above, the nematic liquid crystal is
Note that the direction of twisting toward the other substrate is positive.
The reference line defined in the substrate plane and the one substrate
The angle between the long axis direction of the adjacent liquid crystal molecules is φ_LC,
Angle between the reference line and the direction of the slow axis of the polymer film
Degree φ_F, The reference line and the absorption axis of the polarizing film or
Is the direction of the transmission axis_PAnd φ_F−φ_LCBut -40
゜ ~ -25 ゜, φ_P−φ_FIs between + 50 ° and + 80 °
And features. With this configuration,
Normally white type that can change achromatic black and white
Reflective liquid crystal display device of the present invention.

Here, it is optically equivalent to take φ _P in the direction of the absorption axis and in the direction of the transmission axis.

Further, a reflection type liquid crystal display device according to another configuration of the present invention comprises a liquid crystal cell in which nematic liquid crystal is sealed between a pair of substrates, a polarizing film disposed on one substrate side of the liquid crystal cell, A polymer film disposed between the polarizing film and the liquid crystal cell; and a light reflecting means disposed on the other substrate side, wherein a twist angle of the nematic liquid crystal between the pair of substrates is 0 ° to 90 °. °, the product Δn _LC · d _LC of the nematic liquid crystal of the birefringence [Delta] n _LC of the liquid crystal layer thickness d _LC is 0.20～0.30Myuemu, the product [Delta] n
_LC / d _LC and retardation R of the polymer film
A _Film and by R _{Fi lm} -Δn _LC · d _LC and defined by the birefringence difference ΔR is -0.20μm~-0.05μm, the nematic liquid crystal is the one substrate side when viewed from the substrate side of the one The direction of twisting from the other substrate side to the positive is defined as positive, and the angle formed between the reference line defined in the substrate plane and the major axis direction of the liquid crystal molecules closest to the one substrate is φ _LC , When the angle between the reference line and the direction of the slow axis of the polymer film is φ _F , and the direction of the absorption axis or the transmission axis of the reference line and the polarizing film is φ _P , φ _F
−φ _LC is + 65 ° to + 105 °, φ _P −φ _F is −60 ° to
-90 °. With such a configuration, it is possible to provide a normally white reflective liquid crystal display element which is bright and capable of changing achromatic black and white.

Here, the retardation R _Film of the polymer film is a refractive index in the slow axis direction in the plane of the polymer film.
(Extraordinary index) and n _x, the refractive index of the fast axis direction (ordinary refractive index) n _y, the film thickness is taken as d _Film, R _Film =
It can be represented as _{(n x -n y) · d} Film.

In the reflection type liquid crystal display device of the present invention,
Preferably, the twist angle of the nematic liquid crystal is 30 ° to 65 °, and R _Film is 0.10 μm to 0.30 μm. According to this preferred example, even better characteristics can be obtained.

In the reflection type liquid crystal display device, the polymer film is preferably made of at least one selected from polycarbonate, polyarylate and polysulfone. According to this preferred example, an achromatic black display with a sufficiently low reflectance and an achromatic white display with a high reflectance can be obtained, and a reflective liquid crystal display device with high contrast can be obtained.

Further, in the reflection type liquid crystal display device is preferably Z factor Q _Z of the polymer film is 1.0 to 3.0. Here, Q _Z is space coordinate system defining the direction normal to the film plane as z-axis (x, y, z) the refractive index of each axis direction in the n _x, the n _y and n _z (n _x slow axis Direction, and n _y is the refractive index in the fast axis direction)
A _{Q Z = (n x -n z} ) / coefficients indicated by (n _x -n _y). According to this preferred example, it is possible to obtain a reflective liquid crystal display element in which the reflectance changes little with the viewing angle. From the same viewpoint, Q _Z is more preferably 1.0 to 2.0.

Further, in the reflection type liquid crystal display device, by arranging a scattering film on the one substrate side, it is possible to obtain a bright display by condensing ambient light of the panel. This scattering film is preferably disposed between the polymer film and one of the substrates from the viewpoint of suppressing blurring of the displayed image. Further, the scattering film is preferably a forward scattering film. As the forward scattering film, a film having little forward scattering characteristics and strong forward scattering characteristics is preferable.

In the reflection type liquid crystal display device, it is preferable that the light reflection means includes at least one metal selected from aluminum and silver as a component, and furthermore, the light reflection means also serves as the electrode on the other substrate side. It is preferably a metal electrode.

The metal electrode preferably has a mirror-like surface, especially in the case of a liquid crystal display device provided with the above-mentioned scattering film. According to this preferred example, the disturbance of the alignment of the liquid crystal is small, and natural visibility can be obtained.
On the other hand, particularly in the case of a reflection type liquid crystal display element not using a scattering film, it is preferable to arrange a scattering film on the metal electrode or to impart diffuse reflection to the metal electrode itself.
As the metal electrode having a diffuse reflection property, for example, it is preferable that the surface is provided with irregularities such that the average inclination angle is 3 ° to 12 °. According to these preferred examples, it is possible to obtain a reflection type liquid crystal display device having natural viewing characteristics.

Further, a reflection type liquid crystal display element having a configuration in which the other substrate is a transparent substrate and light reflecting means such as a diffuse reflection plate is arranged outside the transparent substrate may be used. In this case, a transparent electrode is used for the other substrate. When such a configuration is adopted, it is preferable to interpose an air layer between the transparent substrate and the diffuse reflection plate.
According to this preferred example, the diffusion effect can be further increased.

In the reflection type liquid crystal display device, a color filter may be provided to provide a reflection type color liquid crystal display device, or a black and white mode liquid crystal display device may be provided without a color filter. In the latter case, a bright reflective liquid crystal display device can be obtained due to a particularly high reflectance of white display. In the former case, for example, full-color display of 64 gradations is possible due to the characteristic of changing achromatically from white to black.

In the reflection type liquid crystal display device, an active matrix type reflection type liquid crystal display device driven by a non-linear element such as a TFT arranged in a matrix by arranging a non-linear element on the other substrate side. It can be. In this case, particularly, a configuration in which an insulating flattening film is formed on the non-linear element, and the non-linear element and the electrode on the other substrate side are electrically connected through a contact hole formed in the flattening film. Is preferable. According to this preferred example, active driving with a high aperture ratio becomes possible, and a reflection type liquid crystal display device having a high reflectance can be obtained.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing a schematic configuration of a reflection type liquid crystal display device according to a first embodiment. 10 is a polarizing film, 11 is a polymer film, 1
2 is a scattering film layer, 13 is an upper transparent substrate, 14 is a color filter layer, 15a and 15b are alignment layers, 16 is a transparent electrode, 17 is a liquid crystal layer (thickness _dLC ), 18 is a metal reflective electrode,
Reference numeral 9 denotes a lower substrate.

FIG. 2 is an optical configuration diagram of the reflection type liquid crystal display device of the first embodiment. 20 is a reference line, 21 is the orientation direction of liquid crystal molecules closest to the lower substrate, 22 is the orientation direction of liquid crystal molecules closest to the upper transparent substrate, 23 is the slow axis direction of the polymer film, and 24 is the orientation direction of the upper polarizing film. Shows the absorption axis direction. Further, φ _LC0 is the alignment direction 21 of the liquid crystal molecules closest to the lower substrate 19, φ _LC is the alignment direction 22 of the liquid crystal molecules closest to the upper transparent substrate 13, and φ _F is the polymer film 11.
The slow axis direction 23, phi _P indicates the absorption axis or direction 24 of the transmission axis, the angle measured from the reference line 20, respectively of the polarizing film 10. The angle is defined as positive in the twist direction of the liquid crystal represented by Ω _LC (the direction in which liquid crystal molecules are twisted from the upper transparent substrate to the lower substrate).

An alkali-free glass substrate (for example, 1737: manufactured by Corning Incorporated) is used as the upper transparent substrate 13 and the lower substrate 19, and a pigment dispersion type red, green, and blue color filter layer 14 is formed on the upper transparent substrate 13. A pixel having a stripe arrangement was formed by photolithography, and a pixel electrode was formed thereon using indium, tin, and oxide as a transparent electrode 16. On the lower substrate 19, a mirror-reflective metal reflective electrode 18 was formed by depositing titanium to a thickness of 300 nm and aluminum to a thickness of 200 nm.

A 5% by weight solution of polyimide γ-butyrolactone was printed on the transparent electrode 16 and the metal reflective electrode 18 and cured at 250 ° C., and then a rayon cloth was used so as to realize a predetermined twist angle. The alignment layers 15a and 15b were formed by performing an alignment treatment by a rotary rubbing method.

Then, a thermosetting sealing resin (for example, Stract Bond: manufactured by Mitsui Toatsu Chemicals, Inc.) containing 1.0% by weight of glass fiber having a predetermined diameter is printed on the peripheral portion on the upper transparent substrate 13. Then, resin beads having a predetermined diameter are sprayed on the lower substrate 19 at a rate of 100 to 200 beads / mm ² , the upper transparent substrate 13 and the lower substrate 19 are bonded to each other, and the sealing resin is cured at 150 ° C. After that, Δn _LC = 0.
A liquid crystal obtained by mixing a chiral liquid crystal in a fluorine ester type nematic liquid crystal of No. 09 with a chiral liquid crystal having a chiral pitch of 80 μm was vacuum-injected, sealed with an ultraviolet curable resin, and then cured by ultraviolet light.

On the upper transparent substrate 13 of the liquid crystal cell 1 thus formed, an isotropic forward scattering film is adhered as the scattering film layer 12, and one polycarbonate film as the polymer film 11 is formed thereon. The polarizer is stuck so that the phase axes are at a predetermined angle, and a neutral gray polarizing film (SQ-1852AP manufactured by Sumitomo Chemical Co., Ltd.) is subjected to anti-glare (AG) and anti-reflection (AR) treatment as the polarizing film 10. This was attached so that the direction of the absorption axis or the transmission axis was at a predetermined angle.

Φ _LC0 = -67.5 °, φ _LC = 67.5
゜, Ω _LC = 45.0 °, φ _F = 33.0 °, φ _P = 96.
0 °, ΔR = R _Film− Δn _LC · d _LC −0.10μ
m, while changing Δn _LC · d _LC and measuring the optical characteristics in the reflection mode, 0.20 μm to
In the range of 0.30 μm, a normally white mode reflective liquid crystal display device capable of obtaining achromatic black with low reflectance and achromatic white with high reflectance was realized. This is because there is a difference in the birefringence of the liquid crystal enough to obtain white and black, and it is within a range in which coloring due to the birefringence of the liquid crystal can be compensated.

Further, ΔR is −0.20 μm to 0.05 μm.
When m is satisfied, voltage is applied from white display to black display
The color of the display is practically within the range of achromatic color
It was confirmed that it changed. This means that ΔR is -0.20
μm to 0.05 μm, φ _F−φ_LCFrom -40 ° to -2
By setting it within the range of 5mm, it will be especially
In addition, the birefringence of the liquid crystal layer during black display when the on-voltage is applied
Coloration can be eliminated. This allows for reflection
Achromatic black display with low reflectance and achromatic white display with high reflectance
High-contrast reflective liquid crystal display device
Was.

Next, the characteristics when the twist angle Ω _{LC of the} liquid crystal was changed were examined. In the first embodiment of the present invention, good characteristics were obtained when the twist angle was in the range of 0 ° to 90 °. Was confirmed to be obtained. Particularly good characteristics were obtained when the twist angle Ω _LC was 30 ° to 65 °.

Then, R _Film is 0.10 μm to 0.30 μm.
It was confirmed that the black reflectance when the on-voltage was applied can be particularly reduced when the thickness of μm is satisfied.

Here, in particular, Δn _LC · d _LC = 0.270 μm
m, R _Film = 0.170 μm, φ _LC 0 = −67.5 °,
φ _LC = 67.5 °, Ω _LC = 45.0 °, φ _F = 33.0
The results of measuring the optical characteristics when {, φ _P = 96.0} are shown. At this time, ΔR = R _Film− Δn
_LC · d _LC = −0.100 μm, φ _F −φ _LC = −34.5
゜, φ _P −φ _F = + 63.0 °, which satisfies the condition confirmed above.

FIG. 3 is a characteristic diagram showing the relationship between the reflectance and the applied voltage of the reflection type liquid crystal display device of the first embodiment. As for the frontal characteristics, the reflectance of white converted to a Y value was 18.2%, and the contrast was 15.8. In addition, since the color changes from black to white in an achromatic color, it was confirmed that 64 gradation full-color display was possible.

Further, with the above structure, the color filter layer 1
When the reflective liquid crystal display element except for No. 4 was manufactured, a contrast of 15.3 and a reflectance of 34.9% in terms of Y value of white were obtained in frontal characteristics.

In the above configuration, the scattering film layer 1
2 was disposed between the polymer film 11 and the upper transparent substrate 13, but when the scattering film layer 12 was disposed on the polarizing film 10, the polarizing film 11 and the polymer film 1 were also disposed.
The same characteristics were obtained when the arrangement was made between the two.

In this embodiment, polycarbonate is used as the polymer film. However, the effects of the present invention are not limited thereto. For example, similar effects can be obtained by using polyarylate or polysulfone. I confirmed that I can do it.

In this embodiment, a metal reflective electrode containing aluminum as a component is used as a reflective electrode. However, the effect of the invention is not limited to this. For example, a metal reflective electrode containing silver as a component is used. Similar effects can be obtained by using an electrode or the like.

(Second Embodiment) FIG. 4 is a sectional view showing a schematic configuration of a reflection type liquid crystal display device according to a second embodiment. 40 is a polarizing film, 41 is a polymer film, 4
3 is an upper transparent substrate, 44 is a color filter layer, 45a,
45b is an alignment layer, 46 is a transparent electrode, 47 is a liquid crystal layer, 48
Indicates a metal reflective electrode, and 49 indicates a lower substrate.

The optical configuration of the second embodiment is the same as that of the first embodiment, and is the same as the optical configuration of the reflection type liquid crystal display element shown in FIG.

A non-alkali glass substrate (for example, 1737: manufactured by Corning Incorporated) is used as the upper transparent substrate 43 and the lower substrate 49, and a pigment dispersion type red, green, and blue color filter layer 44 is formed on the upper transparent substrate 43. A pixel having a stripe arrangement was formed by photolithography, and a pixel electrode was formed thereon using indium, tin, and oxide as a transparent electrode 46. On the lower substrate 49, a film is formed by evaporating titanium to a thickness of 300 nm and aluminum to a thickness of 200 nm, and further roughening the surface so as to have an average inclination angle of 3 ° to 12 °, thereby diffusing (scattering). ) A reflective metal reflective electrode 48 was formed.

A 5 wt% solution of γ-butyrolactone of polyimide is printed on the transparent electrode 46 and the metal reflective electrode 48, cured at 250 ° C., and then rotated using a rayon cloth so as to realize a predetermined twist angle. The alignment layers 45a and 45b were formed by performing an alignment treatment by a rubbing method.

Then, a thermosetting sealing resin (for example, Stract Bond: manufactured by Mitsui Toatsu Chemicals, Inc.) in which glass fiber of a predetermined diameter is mixed at 1.0% by weight is printed on the peripheral portion on the upper transparent substrate 43. Then, resin beads having a predetermined diameter are sprayed on the lower substrate 49 at a rate of 100 to 200 beads / mm ² , the upper transparent substrate 43 and the lower substrate 49 are bonded to each other, and the sealing resin is cured at 150 ° C. After that, Δn _LC = 0.
A liquid crystal obtained by mixing a chiral liquid crystal with a fluorine ester type nematic liquid crystal of No. 09 so that the chiral pitch becomes 80 μm was vacuum-injected, sealed with an ultraviolet curable resin, and then cured with ultraviolet light.

On the upper transparent substrate 43 of the liquid crystal cell 4 thus formed, polycarbonate is adhered as the polymer film 41 so that the slow axis is at a predetermined angle. Film (SQ-1852AP manufactured by Sumitomo Chemical Co., Ltd.)
Anti-glare (AG) and anti-reflection (AR)
The treated product was affixed so that the direction of the absorption axis or the transmission axis was at a predetermined angle.

Φ _LC0 = -67.5 °, φ _LC = 67.5
゜, Ω _LC = 45.0 °, φ _F = 33.0 °, φ _P = 96.
0 °, ΔR = R _Film− Δn _LC · d _LC −0.10μ
m, while changing Δn _LC · d _LC and measuring the optical characteristics in the reflection mode, 0.20 μm to
In the range of 0.30 μm, a normally white mode reflective liquid crystal display device capable of obtaining achromatic black with low reflectance and achromatic white with high reflectance was realized. This is because there is a difference in the birefringence of the liquid crystal enough to obtain white and black, and it is within a range in which coloring due to the birefringence of the liquid crystal can be compensated.

Further, ΔR is -0.20 μm to 0.05 μm.
When m is satisfied, voltage is applied from white display to black display
The color of the display is practically within the range of achromatic color
It was confirmed that it changed. This means that ΔR is -0.20
μm to 0.05 μm, φ _F−φ_LCFrom -40 ° to -2
By setting it within the range of 5mm, it will be especially
In addition, the birefringence of the liquid crystal layer during black display when the on-voltage is applied
Coloration can be eliminated. This allows for reflection
Achromatic black display with low reflectance and achromatic white display with high reflectance
High-contrast reflective liquid crystal display device
Was.

Next, the characteristics when the twist angle Ω _{LC of the} liquid crystal was changed were examined. According to the first embodiment of the present invention, good characteristics were obtained when the twist angle was in the range of 0 ° to 90 °. Was confirmed to be obtained. Particularly good characteristics were obtained when the twist angle Ω _LC was 30 ° to 65 °.

Then, R _Film is 0.10 μm to 0.30 μm.
It was confirmed that the black reflectance when the on-voltage was applied can be particularly reduced when the thickness of μm is satisfied.

Here, in particular, Δn_LC・ D_LC= 0.270μ
m, R_Film= 0.170 μm, φ_LC0 = -67.5 °,
φ_LC= 67.5 ゜, Ω_LC= 45.0 °, φ_F= 33.0
゜, φ _P= 96.0 ° was measured.
I will show the result. At this time, ΔR = R_Film−Δn
_LC・ D_LC= −0.100 μm, φ_F−φ_LC= -34.5
゜, φ_P−φ_F= + 63.0 ° and the condition confirmed above
Are met.

At this time, in terms of the frontal characteristics, the reflectance in terms of the Y value of white was 17.1%, and the contrast was 15.4. In addition, since the color changes from black to white in an achromatic color, it was confirmed that 64 gradation full-color display was possible.

In the above configuration, the color filter layer 1
When a reflective liquid crystal display element excluding No. 4 was prepared, a contrast of 15.1 and a reflectance of 33.4% in terms of Y value of white were obtained in frontal characteristics.

In this embodiment, polycarbonate is used as the polymer film. However, the effects of the present invention are not limited thereto. For example, similar effects can be obtained by using polyarylate or polysulfone. I confirmed that I can do it.

In this embodiment, a metal reflective electrode containing aluminum as a component is used as a reflective electrode. However, the effect of the invention is not limited to this. For example, a metal reflective electrode containing silver as a component is used. Similar effects can be obtained by using an electrode or the like.

(Third Embodiment) The reflection type liquid crystal display device of the third embodiment has the same fabrication and structure as those of the first embodiment, and the reflection type liquid crystal display device shown in FIG. It has a cross section of the element and an optical configuration of a reflective liquid crystal display element similar to that of FIG.

Φ _LC0 = -67.5 °, φ _LC = 67.5
゜, Ω _LC = 45.0 °, φ _F = 155.0 °, φ _P = 9
0.0 ° and ΔR = R _Film −Δn _LC · d _LC −0.1
When the optical characteristics were measured in the reflection mode while changing Δn _LC · d _LC while satisfying 0 μm, 0.20 μm
A normally white mode reflection type liquid crystal display device capable of obtaining achromatic black with low reflectance and achromatic white with high reflectance in the range of 0.30 μm was realized.
This is because there is a difference in the birefringence of the liquid crystal enough to obtain white and black, and it is within a range in which coloring due to the birefringence of the liquid crystal can be compensated.

Further, ΔR is set to −0.20 μm to 0.05 μm.
When m is satisfied, voltage is applied from white display to black display
The color of the display is practically within the range of achromatic color
It was confirmed that it changed. This means that ΔR is -0.20
μm to 0.05 μm, φ _F−φ_LC+ 65 ° to +1
Within the range of 05 °, during the transition from white to black,
In particular, the birefringence of the liquid crystal layer during black display when applying on-voltage
This is because coloring due to folding can be eliminated. As a result,
Achromatic black display with low emissivity and achromatic white table with high reflectivity
Can realize a reflective LCD device with high contrast
Was.

Next, the characteristics when the twist angle Ω _{LC of the} liquid crystal was changed were examined. In the third embodiment of the present invention, good characteristics were obtained when the twist angle was in the range of 0 ° to 90 °. Was confirmed to be obtained. Particularly good characteristics were obtained when the twist angle Ω _LC was 30 ° to 65 °.

Then, RFilm is 0.10 μm to 0.30
It was confirmed that the black reflectance when the on-voltage was applied can be particularly reduced when the thickness of μm is satisfied.

Here, in particular, Δn _LC · d _LC = 0.270 μm
m, R _Film = 0.170 μm, φ _LC 0 = −67.5 °,
φ _LC = 67.5 °, Ω _LC = 45.0 °, φ _F = 155.
The results of measuring the optical characteristics when 0 ° and φ _P = 90.0 ° are shown. At this time, ΔR = R _Film− Δ
n _LC · d _LC = −0.10 μm, φ _F −φ _LC = 87.5
゜, φ _P −φ _F = −65.0 °, which satisfies the conditions confirmed above.

FIG. 5 is a characteristic diagram showing the relationship between the reflectance and the applied voltage of the reflection type liquid crystal display device of the third embodiment. With respect to the front characteristics, the reflectance of white converted to a Y value was 18.1%, and the contrast was 15.6. In addition, since the color changes from black to white in an achromatic color, it was confirmed that 64 gradation full-color display was possible.

In the above configuration, the color filter layer 1
When the reflective liquid crystal display element except for No. 4 was prepared, a contrast of 15.1 and a reflectance of 34.3% in terms of white Y value were obtained in terms of frontal characteristics.

In the above configuration, the scattering film layer 1
2 was disposed between the polymer film 11 and the upper transparent substrate 13, but when the scattering film layer 12 was disposed on the polarizing film 10, the polarizing film 11 and the polymer film 1 were also disposed.
The same characteristics were obtained when the arrangement was made between the two.

In this embodiment, polycarbonate is used as the polymer film. However, the effects of the present invention are not limited thereto. For example, similar effects can be obtained by using polyarylate or polysulfone. I confirmed that I can do it.

In this embodiment, a metal reflective electrode containing aluminum as a component is used as a reflective electrode. However, the effect of the invention is not limited to this. For example, a metal reflective electrode containing silver as a component is used. Similar effects can be obtained by using an electrode or the like.

(Fourth Embodiment) The reflection type liquid crystal display device of the fourth embodiment is basically manufactured and structured in the first mode.
This embodiment has a cross section of the reflection type liquid crystal display device shown in FIG. 1 and an optical configuration of the reflection type liquid crystal display device similar to that of FIG.

FIG. 6A is a characteristic diagram showing a change in reflectance of black when an ON voltage is applied to a change in viewing angle in the right direction.

FIG. 6B is a characteristic diagram showing a change in the reflectance of black when an ON voltage is applied to a change in the viewing angle in the upward direction.

In the present embodiment, Δn _LC · d _LC = 0.2
70 μm, R _Film = 0.170 μm, φ _LC0 = −67.
5 °, φ _LC = 67.5 °, Ω _LC = 45 °, φ _F1 = 33.
0 °, as phi _P = 96.0 °, was examined by changing the Z coefficient Q _z of the polymer film 11, Q _z is 1.0
When it was 3.0, it was found that a change in the reflectance with respect to the change in the viewing angle was small and good characteristics were obtained.

In particular, Q _z is set to 0.3, 0.5,
The change in reflectance with the viewing angle of black display at 1.0 and 1.5 was examined in detail.

[0078] Looking at FIGS. 6a and 6b, the which affect the polymer film 11 is the viewing angle characteristic change, it can be seen that the reflectance characteristics of good black little viewing angle dependence when Q _z is greater can be obtained . Based on this result, in particular, when Q _z satisfies 1.0 to 2.0, it was confirmed that obtained a more desirable viewing angle characteristic.

(Fifth Embodiment) FIG. 7 is a sectional view showing a schematic structure of a reflection type liquid crystal display device according to a fifth embodiment. 70 is a polarizing film, 71 is a polymer film, 7
3 is an upper transparent substrate, 74 is a color filter layer, 75a,
75b is an alignment layer, 76 is a transparent electrode, 77 is a liquid crystal layer, 78
Denotes a transparent electrode, 79 denotes a lower transparent substrate, and 72 denotes a diffuse reflection plate.

The optical configuration of the reflection type liquid crystal display device is the same as that of FIG.

The upper transparent substrate 73 and the lower transparent substrate 79
A non-alkali glass substrate (for example, 1737: manufactured by Corning Incorporated) was used as a color filter layer 74 on an upper transparent substrate 73. The color filter layer 74 was formed of a pigment dispersion type having a red, green, and blue stripe arrangement by photolithography.

Then, pixel electrodes were formed on the color filter layer 74 and the lower transparent substrate 79 as indium, tin and oxide as the transparent electrodes 76 and 78. On the transparent electrodes 76 and 78, a 5% by weight solution of γ-butyrolactone of polyimide is printed, cured at 250 ° C., and then subjected to an orientation treatment by a rotary rubbing method using rayon cloth so as to realize a predetermined twist angle. Was performed to form alignment layers 75a and 75b.

The peripheral portion on the upper transparent substrate 73 has a predetermined diameter.
Thermosetting resin containing 1.0% by weight of glass fiber
Resin (for example, Structbond: Mitsui Toatsu Chemicals)
Is printed on the lower substrate 79 and has a predetermined diameter.
100-200 fat beads / mm ^TwoSpray at the rate of
The transparent substrate 73 and the lower substrate 79 are stuck together.
After curing the sealing resin at 50 ° C., Δn_LC= 0.09
Chiral pitch in fluoroester nematic liquid crystal
Vacuum the liquid crystal mixed with chiral liquid crystal to 80μm
Inject and seal with UV curable resin.
Hardened.

On the upper transparent substrate 73 of the liquid crystal cell 7 thus formed, polycarbonate is adhered as the polymer film 71 so that the slow axis is at a predetermined angle, and the polarizing film 70 is neutral gray polarized light. Film (SQ-1852AP manufactured by Sumitomo Chemical Co., Ltd.)
Anti-glare (AG) and anti-reflection (A
R) was applied so that the direction of the absorption axis or the transmission axis was at a predetermined angle.

Under the lower transparent substrate 79, the diffuse reflection plate 7
As No. 2, a silver diffuse reflector was installed.

In this embodiment, Δn _LC · d _LC = 0.
270 μm, R _Film = 0.170 μm, φ _LC0 = −6
7.5 °, φ _LC = 67.5 °, Ω _LC = 45 °, φ _F = 3
3.0 ° and φ _P = 96.0 °.

As described above, when the upper and lower substrates are transparent substrates and transparent electrodes, and the diffuse reflection plate is used on the lower side, some image blurring due to the influence of parallax appears, but the reflection type liquid crystal display element having a natural change in viewing angle characteristics. It was confirmed that it could be obtained.

When the front characteristics were measured, a reflectance of 16.1% in terms of Y value of white and a contrast of 14.3 were obtained.

In the above configuration, the color filter layer 7
When the reflective liquid crystal display element except for No. 4 was prepared, a reflectance of 32.1% and a contrast of 14.0% were obtained in terms of front characteristics in terms of white Y value.

The diffuse reflection plate 72 is connected to the lower transparent substrate 79.
When it is installed under the air, it does not adhere completely with the adhesive, but by putting an air layer between them, the diffusion effect caused by the difference between the refractive index of resin about 1.6 and the refractive index of air 1.0. It was confirmed that a more natural viewing angle characteristic can be obtained by enlarging.

In this embodiment, silver was used as the diffuse reflection plate, but it was confirmed that the same invention effect can be obtained with the aluminum diffusion reflection plate.

(Sixth Embodiment) FIG. 8 is a sectional view showing a schematic configuration of a reflection type liquid crystal display device according to a sixth embodiment. 80 is a polarizing film, 81 is a polymer film, 8
2 is a scattering film layer, 83 is an upper transparent substrate, 84 is a color filter layer, 85a and 85b are alignment layers, 86 is a transparent electrode, 87 is a liquid crystal layer, 88 is a metal reflective electrode, 89 is a lower substrate, and 90 is a gate. Electrode, 91 is a source line, 92 is a thin film transistor element (TFT), 93 is a drain electrode, 94
Indicates a flattening film. 95 is a contact hole. The difference from the first embodiment or the third embodiment is that the metal reflective electrode substrate is electrically connected to the non-linear switching element (TFT) below the flattening film through the contact hole, so that active driving can be performed. That is what we did.

The optical configuration of the reflection type liquid crystal display device of the present embodiment is the same as that of FIG.

A non-alkali glass substrate (for example, 1737: manufactured by Corning Incorporated) is used as the upper transparent substrate 83 and the lower substrate 89. On the upper transparent substrate 83, as a color filter layer 84, a pigment dispersion type of red, green, and blue is used. A pixel having a stripe arrangement was formed by photolithography, and a pixel electrode was formed thereon using indium tin oxide as a transparent electrode 86.

On the lower substrate 89, a gate electrode 90 made of aluminum and tantalum is formed by a predetermined method.
A source electrode 91 and a drain electrode 93 made of titanium and aluminum are arranged in a matrix, and a gate electrode 9 is formed.
A TFT element 92 made of amorphous silicon was formed at each intersection of 0 and the source electrode 91.

A flat photosensitive film 94 is formed by applying a positive photosensitive acrylic resin (for example, FVR: manufactured by Fuji Pharmaceutical Co., Ltd.) on the entire surface of the lower substrate 89 on which the non-linear element is formed. After that, a contact hole 95 was formed on the drain electrode 93 by irradiating ultraviolet rays using a predetermined photomask. Then, on top of that, 300nm titanium
A metal reflective electrode 88 of a specular reflection type was formed by forming a film on which aluminum was vapor-deposited to a thickness of 200 nm.

On the transparent electrode 86 and the metal reflective electrode 88, a 5% by weight solution of polyimide γ-butyrolactone was printed and cured at 250 ° C., and then a rayon cloth was used to achieve a predetermined twist angle. The orientation layers 85a and 85b were formed by performing an orientation treatment by a rotary rubbing method.

Then, a thermosetting sealing resin (for example, Stract Bond: manufactured by Mitsui Toatsu Chemicals, Inc.) containing 1.0 wt% of glass fiber having a predetermined diameter is printed on the peripheral portion on the upper transparent substrate 83. On the lower substrate 89, resin beads having a predetermined diameter were sprayed at a rate of 100 to 200 beads / mm ² , the upper transparent substrate 83 and the lower substrate 89 were bonded to each other, and the sealing resin was cured at 150 ° C. Then, Δn _LC = 0.
A liquid crystal obtained by mixing a predetermined amount of a chiral liquid crystal with a fluorine ester type nematic liquid crystal of No. 09 was vacuum-injected, sealed with an ultraviolet curable resin, and then cured with ultraviolet light.

On the upper transparent substrate 83 of the liquid crystal cell 8 thus formed, an isotropic forward scattering film is adhered as the scattering film layer 82, and the polymer film 8 is placed thereon.
As No. 1, a polycarbonate was stuck so that the slow axis was at a predetermined angle, and a neutral gray polarizing film (manufactured by Sumitomo Chemical Co., Ltd., S
Q-1852AP), which had been subjected to anti-glare (AG) and anti-reflection (AR) treatments, was affixed such that the direction of the absorption axis or transmission axis was at a predetermined angle.

In this embodiment, Δn_LC・ D_LC= 0.270
μm, R_Film= 0.170 μm, φ _LC0= -67.5
゜, φ_LC= 67.5 ゜, Ω_LC= 45.0 °, φ_F= 3
3.0 °, φ_P= 96.0 °.

As for the optical characteristics, active driving was performed in the configuration of the first embodiment, and a full-color display of 64 gradations could be obtained. By forming a metal reflective electrode on the flattening film, an aperture ratio of 97% could be obtained. Therefore, in the front characteristics, the reflectance in terms of white Y value was 17.9%, and the contrast was 15%. Was 0.9.

Note that not only this embodiment but also all the embodiments described so far, by forming a non-linear element such as a TFT on the lower substrate, an active drive reflection type liquid crystal display element can be realized. It can be obtained according to the method described in the present embodiment. Non-linear elements are not limited to amorphous silicon TFTs, but are two-terminal elements (M
IM and thin film diode) and polysilicon TFT
The same effect can be obtained by using such a method.

[0103]

As described above, according to the reflection type liquid crystal display device of the present invention, it is possible to obtain a bright white, high contrast, normally white type reflection type liquid crystal display device capable of changing achromatic black and white. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a reflective liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an optical configuration diagram of the reflective liquid crystal display device of FIG.

FIG. 3 is a characteristic diagram showing an example of the relationship between the reflectance and the applied voltage of the reflective liquid crystal display device of FIG.

FIG. 4 is a cross-sectional view showing a schematic configuration of a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing an example of a relationship between a reflectance and an applied voltage of a reflective liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a characteristic diagram illustrating an example of a change in black reflectance when an ON voltage is applied to a change in the viewing angle in the right direction (a) or the upward direction (b).

FIG. 7 is a sectional view showing a schematic configuration of a reflective liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating a schematic configuration of a reflective liquid crystal display device according to a sixth embodiment of the present invention.

[Explanation of symbols]

1, 4, 7, 8 Liquid crystal cell 10, 40, 70, 80 Polarizing film 11, 41, 71, 81 Polymer film 12, 82 Scattering film layer 13, 43, 73, 83 Upper transparent substrate 14, 44, 74, 84 color filter layer 15a, 15b, 45a, 45b, 75a, 75b, 8
5a, 85b Alignment layer 16, 46, 76, 86 Transparent electrode 17, 47, 77, 87 Liquid crystal layer 18, 48, 88 Metal reflective electrode 19, 49, 89 Lower substrate 20 Reference line 21 Liquid crystal closest to lower substrate Orientation direction of molecules 22 Orientation direction of liquid crystal molecules closest to upper substrate 23 Slow axis direction of polymer film 24 Absorption axis direction of upper polarizing film 72 Diffuse reflector 78 Transparent electrode 79 Lower transparent substrate 90 Gate electrode 91 Source line 92 TFT element 93 Drain electrode 94 Flattening film 95 Contact hole

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/136 500 G02F 1/136 500 (72) Inventor Yoshio Iwai 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Within Sangyo Co., Ltd. (72) Inventor Tetsu Ogawa 1006 Kadoma, Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.F-term (reference) KA02 KA03 LA17 2H092 JA24 JB07 PA02 PA08 PA11 PA12

Claims (19)

[Claims] 1. A nematic liquid crystal is sealed between a pair of substrates.
And a liquid crystal cell arranged on one substrate side of the liquid crystal cell.
Polarizing film, the polarizing film and the liquid crystal cell
And the other side of the substrate
And a light reflecting means disposed, wherein a twist of the nematic liquid crystal between the pair of substrates is provided.
Angle: 0 ° to 90 °, birefringence Δ of the nematic liquid crystal
n_LCAnd liquid crystal layer thickness d_LCAnd the product Δn_LC・ D_LCIs 0.20
0.30 μm, the product Δn_LC・ D_LCAnd the polymer fill
Retardation R_FilmAnd R_Film−Δn_LC・
d_LCBirefringence difference ΔR defined as -0.20 μm
0.05 μm, and the nematic liquid crystal is
Twist from one substrate side to the other substrate side
With the reference direction defined in the substrate plane
The long axis direction of the liquid crystal molecules closest to the one substrate;
Φ _LC, The retardation between the reference line and the polymer film
The angle between the axis direction and φ_F, The reference line and the polarization filter.
The direction of the film's absorption axis or transmission axis is φ_PAnd when
And φ_F−φ _LCIs -40 ° to -25 °, φ_P−φ_FIs +5
A reflection type liquid crystal display characterized by a range of 0 ° to + 80 °
element. 2. A nematic liquid crystal is sealed between a pair of substrates.
And a liquid crystal cell arranged on one substrate side of the liquid crystal cell.
Polarizing film, the polarizing film and the liquid crystal cell
And the other side of the substrate
And a light reflecting means disposed, wherein a twist of the nematic liquid crystal between the pair of substrates is provided.
Angle: 0 ° to 90 °, birefringence Δ of the nematic liquid crystal
n_LCAnd liquid crystal layer thickness d_LCAnd the product Δn_LC・ D_LCIs 0.20
0.30 μm, the product Δn_LC・ D_LCAnd the polymer fill
Retardation R_FilmAnd R_Film−Δn_LC・
d_LCBirefringence difference ΔR defined as -0.20 μm
0.05 μm, and the nematic liquid crystal is
Twist from one substrate side to the other substrate side
With the reference direction defined in the substrate plane
The long axis direction of the liquid crystal molecules closest to the one substrate;
Φ _LC, The retardation between the reference line and the polymer film
The angle between the axis direction and φ_F, The reference line and the polarization filter.
The direction of the film's absorption axis or transmission axis is φ_PAnd when
And φ_F−φ _LCIs + 65 ° to + 105 °, φ_P−φ_FBut-
A reflection type liquid crystal table having an angle of 60 ° to -90 °
Indicating element. 3. The reflection type liquid crystal display device according to claim 1, wherein the twist angle of the nematic liquid crystal is 30 ° to 65 °. 4. The method according to claim 1, wherein the R _film has a thickness of 0.10 μm to 0.30 μm.
3. The reflective liquid crystal display device according to claim 1, wherein m is m. 5. The reflective liquid crystal display device according to claim 1, wherein the polymer film is made of at least one selected from polycarbonate, polyarylate, and polysulfone. 6. The polymer film having a Z coefficient Q _Z of 1.
The reflective liquid crystal display device according to any one of claims 1 to 5, wherein the ratio is from 0 to 3.0. However, the Q _Z is space coordinate system defining the direction normal to the film plane as z-axis (x, y, z) the refractive index of each axis direction in the n _x, the n _y and n _z (n _x slow axis direction of the refractive index, n _y by using the refractive index of the fast axis direction),
A _{Q Z = (n x -n z} ) / coefficients indicated by (n _x -n _y). 7. The reflective liquid crystal display device according to claim 6, wherein said Q _Z is 1.0 to 2.0. 8. The reflection type liquid crystal display device according to claim 1, wherein a scattering film is disposed on the one substrate side. 9. The reflective liquid crystal display device according to claim 8, wherein the scattering film is disposed between the polymer film and the one substrate. 10. The reflective liquid crystal display device according to claim 8, wherein the scattering film is a forward scattering film. 11. The reflective liquid crystal display device according to claim 1, wherein said light reflecting means is a metal electrode containing at least one metal selected from aluminum and silver as a constituent element. 12. The reflective liquid crystal display device according to claim 11, wherein the surface of the metal electrode is mirror-like. 13. The reflection type liquid crystal display device according to claim 11, wherein a scattering film is disposed on the metal electrode. 14. The reflective liquid crystal display device according to claim 11, wherein the surface of the metal electrode has irregularities with an average inclination angle of 3 ° to 12 °, and diffusely reflects incident light. 15. The other substrate is a transparent substrate,
The light reflecting means is arranged outside the transparent substrate.
11. The reflective liquid crystal display device according to any one of items 10. 16. The reflection type liquid crystal display device according to claim 15, wherein an air layer is interposed between said transparent substrate and said light reflecting means. 17. The reflection type liquid crystal display device according to claim 1, wherein a color filter is arranged on the one substrate side. 18. The reflection type liquid crystal display element according to claim 1, wherein a non-linear element is arranged on the other substrate side. 19. An insulating flattening film is formed on the non-linear element, and the non-linear element and the electrode on the other substrate are electrically connected through a contact hole formed in the flattening film. 19. The reflective liquid crystal display device according to 18.